1. Field of the Invention:
This invention relates to recording apparatus in which the recording position is shifted by moving a recording head relative to the record bearing medium.
2. Description of the Prior Art:
Apparatuses that record information such as video signals on a rotary magnetic sheet shaped or disc shaped record bearing medium, form one of two types of recording tracks, concentric or spiral. In an apparatus which successively forms concentric round recording tracks, the magnetic recording head is intermittently moved radially of the record bearing medium.
When the head is moved in this intermittent manner, the head and the head carrier generally behave as shown in FIG. 1, where the abscissa is in time and the ordinate is in the distance the head moves. Taking the start of the current supply to a head-moving drive source (for example, a plunger) as the origin O, along the time axis, the time T from the start of current supply to initiation of an information signal recording operation is composed of three components. The first component is a time delay t1 from the start of the current supply to the start of motion of the driving system, the second a travel time t2 necessary for the head to travel a prescribed track pitch, and the third a time t3 from the moment at which the head has arrived at a recording position to the moment at which, as vibrations substantially end, the head reaches a substantially stable state. Therefore, from the start of current supply to the head, the initiation of a signal recording operation by the head must be deferred for the duration of of the time T.
On the other hand, when the drive source for moving the head is in the form of an electromagnetic device such as a plunger or stepping motor, its control generally employs an open loop. Then, the temperature and humidity of the atmosphere in which the recording apparatus is used, the position the recording apparatus assumes when it is held by hand, and the actual voltage of the electrical power source or battery influence the delay time t1 and the travel time t2, and hence the time T from the start of current supply to the start of recording.
In prior art recording apparatuses of this kind, timing of the recording involved presuming the maximum possible range of variation of the time T. This, however, lengthens the cycle of the head travel followed by recording with a consequent decrease in the amount of information recorded per unit of time. If the timing of the recording is determined by presuming the worst conditions, the head operating mechanism operates in the usual good conditions without making the most of its ability. Such use is inefficient.